Air conditioner

ABSTRACT

An air conditioner of variable capacity type comprises a variable-capacity compressor capable of varying capacity in two levels by switching between FULL and SAVE. The variable-capacity compressor can start operation at SAVE so as to allow the air conditioner to start operation without causing a shutdown of the variable-capacity compressor in an overloaded condition or in a low power-supply voltage environment.

FIELD OF THE INVENTION

The present invention relates to an air conditioner of variable capacitytype including a compressor capable of switching a compressor dischargevolume between high and low levels.

BACKGROUND OF THE INVENTION

Conventional air conditioners comprise a compressor capable of varyingcapacity in two levels by switching the compressor discharge volumebetween full-power operation (hereinafter, FULL) of high level andpower-saving operation (hereinafter, SAVE) of low level. These airconditioners start operation with the compressor at FULL. When such anair conditioner starts operation in an environment where both the indoortemperature and the outdoor temperature are high (that is, in anoverloaded environment), too high a pressure of the compressor or a lowpower-supply voltage may cause an increase in the starting currentvalue. The increase in the starting current value can extremely decreasethe motor output in the compressor, causing the motor to make a forcedstop or a so-called “breakdown”, thereby interrupting the compressionworkings. To avoid this from happening, the air conditioner isstructured as follows. When the starting current value is increased inan overloaded condition or in a low power-supply voltage environment, anoverload relay (hereinafter, OLP) as a protection device is actuated toprotect the compressor. As a result, the compressor energizing circuitis shut off to prevent the motor winding from burning or seizing.

When the OLP is naturally cooled, the compressor energizing circuit thusshut off is restored and supplied with a current, as shown in FIG. 20.This operation is repeated hereinafter.

The compressor protector with the conventional OLP has the followingproblem. When the power supply voltage is low, the refrigerating cycleis likely to be overloaded and the compressor is likely to be locked up.In these situations, the OLP is actuated repeatedly. To solve thisproblem, Japanese Patent Unexamined Publication No. H07-174392 disclosesan air conditioner with an OLP actuating means for detecting OLPactuation and a restart-voltage changing means.

The aforementioned conventional structure, however, has the followingproblems. First, when an overload condition or a low power-supplyvoltage environment increases the starting current, the OLP is actuatedto protect the compressor. This prevents the compressor from startingoperation and therefore prevents the air conditioner from startingoperation. Second, when the power supply voltage is extremely low, thelow voltage protection means is actuated, and when the refrigeratingcycle is overloaded, the OLP is actuated. These situations cause thecompressor and the air conditioner main body to be started and stoppedrepeatedly, thereby damaging the compression mechanism part.

SUMMARY OF THE INVENTION

The present invention provides an air conditioner of variable capacitytype which comprises a compressor capable of varying capacity in twolevels by switching between full-power operation and power-savingoperation and which is provided with a voltage detector, wherein when asupply voltage is below a predetermined value, the compressor isoperated at the power-saving operation. With this structure, when thesupply voltage is decreased and the operating current is increased, thecompressor can be operated at the power-saving operation to reduce thecompression load and hence the current value. As a result, the airconditioning operation can be continued without causing a shutdown ofthe compressor.

The air conditioner of the present invention may be provided with acurrent detector, so that when an operating current exceeds apredetermined value, the compressor can be operated at the power-savingoperation. As a result, when the supply voltage is reduced and theoperating current is increased, the compressor can be operated at thepower-saving operation to reduce the compression load and hence thecurrent value. As a result, the air conditioning operation can becontinued without causing a shutdown of the compressor.

The air conditioner of the present invention may be provided with adischarge pressure detector for the compressor, so that when a dischargepressure exceeds a predetermined value, the compressor can be operatedat the power-saving operation. When the discharge pressure is increasedby an increase in outdoor temperature, the detection of a dischargepressure correlating to the current value makes the compressor operateat the power-saving operation, thereby suppressing an excessive increasein the discharge pressure and reducing the operating current. As aresult, the air conditioning operation can be continued without causinga shutdown of the compressor.

The air conditioner of the present invention may be provided with atemperature detector for an outdoor heat exchanger, so that when thetemperature of the outdoor heat exchanger exceeds a predetermined value,the compressor can be operated at the power-saving operation. When thetemperature of the outdoor heat exchanger is increased by an increase inoutdoor temperature, the detection of the temperature of the outdoorheat exchanger correlating to the current value makes the compressoroperate at the power-saving operation, thereby suppressing an increasein the temperature of the outdoor heat exchanger and reducing theoperating current. As a result, the air conditioning operation can becontinued without causing a shutdown of the compressor.

The air conditioner of the present invention may comprise a compressorcapable of varying capacity in two levels by switching between FULL andSAVE, and the compressor may start operation at SAVE. With thisstructure, in an overloaded condition or in a low power-supply voltageenvironment, the compressor can be operated at SAVE to reduce thecompression load so as to have a low starting current value. As aresult, the air conditioning operation can be continued without causinga shutdown of the compressor.

The air conditioner of the present invention may be provided with aplurality of running capacitors connected to each other to increase acapacitor capacity when the compressor driven by a capacitor start andrun induction motor starts operation at SAVE. With this structure, in anoverloaded condition or in a low power-supply voltage environment, highstarting performance allows the compressor to be started smoothly atSAVE, so that the air conditioner can start operation without causing ashutdown of the compressor.

The air conditioner of the present invention may be a variable capacitytype which comprises a compressor capable of varying capacity in twolevels by switching the compressor discharge volume between FULL of highlevel and SAVE of low level, and which is provided with a voltagedetector. When the supply voltage is below a predetermined value, thecompressor is operated at SAVE and at an increased capacitor capacity.

As a result, when the supply voltage is decreased and the operatingcurrent is increased, the compressor can be operated at SAVE to reducethe compression load and hence the current value. Furthermore, thecapacitor capacity can be increased by providing a plurality of runningcapacitors for the compressor so as to increase the torque of the motorin the compressor, thereby reducing breakdown. As a result, the airconditioning operation can be continued without causing a shutdown ofthe compressor.

The air conditioner of the present invention may be provided with acurrent detector, so that when the operating current exceeds apredetermined value, the compressor is operated at SAVE and at anincreased capacitor capacity. As a result, when the supply voltage isdecreased and the operating current is increased, the compressor can beoperated at SAVE to reduce the compression load and hence the currentvalue. Furthermore, the capacitor capacity can be increased by providinga plurality of running capacitors for the compressor so as to increasethe torque of the motor in the compressor, thereby reducing breakdown.As a result, the air conditioning operation can be continued withoutcausing a shutdown of the compressor.

The air conditioner of the present invention may be provided with adischarge pressure detector for the compressor, so that when thedischarge pressure exceeds a predetermined value, the compressor can beoperated at SAVE and at an increased capacitor capacity.

When the discharge pressure is increased by an increase in outdoortemperature, the detection of a discharge pressure correlating to thecurrent value makes the compressor operate at SAVE, thereby suppressingan excessive increase in the discharge pressure and reducing theoperating current. Furthermore, the capacitor capacity can be increasedby providing a plurality of running capacitors for the compressor so asto increase the torque of the motor in the compressor, thereby reducingbreakdown. As a result, the air conditioning operation can be continuedwithout causing a shutdown of the compressor.

The air conditioner of the present invention may be provided with atemperature detector for the outdoor heat exchanger, so that when thetemperature of the outdoor heat exchanger exceeds a predetermined value,the compressor can be operated at SAVE and at an increased capacitorcapacity. When the temperature of the outdoor heat exchanger isincreased by an increase in outdoor temperature, the detection of thetemperature of the outdoor heat exchanger correlating to the currentvalue makes the compressor operate at SAVE, thereby suppressing anincrease in the temperature of the outdoor heat exchanger and reducingthe operating current. Furthermore, the capacitor capacity can beincreased by providing a plurality of running capacitors for thecompressor so as to increase the torque of the motor in the compressor,thereby reducing breakdown. As a result, the air conditioning operationcan be continued without causing a shutdown of the compressor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart showing the operation of a compressor of a firstembodiment of the present invention.

FIG. 2 is a block diagram relating to a controller of the firstembodiment of the present invention.

FIG. 3 is a flowchart showing the operation of a compressor of a secondembodiment of the present invention.

FIG. 4 is a block diagram relating to a controller of the secondembodiment of the present invention.

FIG. 5 is a flowchart showing the operation of a compressor of a thirdembodiment of the present invention.

FIG. 6 is a block diagram relating to a controller of the thirdembodiment of the present invention.

FIG. 7 is a flowchart showing the operation of a compressor of a fourthembodiment of the present invention.

FIG. 8 is a block diagram relating to a controller of the fourthembodiment of the present invention.

FIG. 9 is a block diagram relating to a controller of a fifth embodimentof the present invention.

FIG. 10 is a flowchart showing the operation of a compressor of a sixthembodiment of the present invention.

FIG. 11 is a block diagram relating to a controller of the sixthembodiment of the present invention.

FIG. 12 is a flowchart showing the operation of a compressor of aseventh embodiment of the present invention.

FIG. 13 is a block diagram relating to a controller of the seventhembodiment of the present invention.

FIG. 14 is a flowchart showing the operation of a compressor of aneighth embodiment of the present invention.

FIG. 15 is a block diagram relating to a controller of the eighthembodiment of the present invention.

FIG. 16 is a flowchart showing the operation of a compressor of a ninthembodiment of the present invention.

FIG. 17 is a block diagram relating to a controller of the ninthembodiment of the present invention.

FIG. 18 is a flowchart showing the operation of a compressor of a tenthembodiment of the present invention.

FIG. 19 is a block diagram relating to a controller of the tenthembodiment of the present invention.

FIG. 20 is an operational block diagram showing a conventional overloadprotector.

REFERENCE MARKS IN THE DRAWINGS

-   1, 11, 20 controller-   2 compressor-   3, 23 voltage detector-   4, 24 current detector-   5, 25 discharge pressure detector-   6, 26 outdoor-heat-exchanger-temperature detector-   10 operation switch-   12 variable-capacity compressor-   13, 22 FULL/SAVE selector-   14 running-capacitor block-   21 variable-volume compressor-   27 compressor-running-capacitor block

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An air conditioner of the present invention comprises the followingcomponents: an indoor blower circuit, an outdoor blower circuit, arefrigerating cycle, and a controller. The indoor blower circuitcomprises an indoor air inlet, an indoor heat exchanger, an indoor airfan, and indoor air outlet. The outdoor blower circuit comprises anoutdoor air inlet, an outdoor heat exchanger, an outdoor air fan, and anoutdoor air outlet. The refrigerating cycle comprises an indoor heatexchanger, an outdoor heat exchanger, a compressor, and a throttle,which are connected by piping. The air conditioner is a variablecapacity type including a compressor capable of varying capacity in twolevels by switching between full-power operation and power-savingoperation. The air conditioner is provided with a voltage detector, sothat when the supply voltage is below a predetermined value, thecompressor can be operated at the power-saving operation. As a result,the air conditioning operation can be continued without causing ashutdown of the compressor in a low voltage environment.

The air conditioner of the present invention may be provided with acurrent detector, so that when the operating current exceeds apredetermined value, the compressor can be operated at the power-savingoperation. As a result, when the operating current is increased in a lowvoltage environment or in an overloaded condition, the air conditioningoperation can be continued without causing a shutdown of the compressor.

The air conditioner of the present invention may be provided with adischarge pressure detector for the compressor, so that when thedischarge pressure exceeds a predetermined value, the compressor can beoperated at the power-saving operation. As a result, even in anoverloaded condition, the air conditioning operation can be continuedwithout causing a shutdown of the compressor.

The air conditioner of the present invention may be provided with atemperature detector for the outdoor heat exchanger, so that when thetemperature of the outdoor heat exchanger exceeds a predetermined value,the compressor can be operated at the power-saving operation. As aresult, even in an overloaded condition, the air conditioning operationcan be continued without causing a shutdown of the compressor.

The air conditioner of the present invention comprises the followingcomponents: an indoor blower circuit, an outdoor blower circuit, arefrigerating cycle, and a controller. The indoor blower circuitcomprises an indoor air inlet, an indoor heat exchanger, an indoor airfan, and indoor air outlet. The outdoor blower circuit comprises anoutdoor air inlet, an outdoor heat exchanger, an outdoor air fan, and anoutdoor air outlet. The refrigerating cycle comprises an indoor heatexchanger, an outdoor heat exchanger, a compressor, and a throttle,which are connected by piping. The air conditioner is provided with acompressor which is capable of varying capacity in two levels byswitching between full-power operation (FULL) and power-saving operation(SAVE) and which starts operation at SAVE. In an overloaded condition orin a low power-supply voltage environment, the compression load can bereduced to make the starting current value low. As a result, the airconditioning operation can be started without causing a shutdown of thecompressor.

The air conditioner of the present invention may be provided with aplurality of running capacitors, so that the capacitor capacity can beincreased by connecting the running capacitors to each other when thecompressor starts operation. Thus, in an overloaded condition or in alow power-supply voltage environment, high starting performance allowsthe compressor to be started smoothly at SAVE, so that the airconditioner can start operation without causing a shutdown of thecompressor.

The air conditioner of the present invention may comprise the followingcomponents: an indoor blower circuit, an outdoor blower circuit, arefrigerating cycle, and a controller. The indoor blower circuitcomprises an indoor air inlet, an indoor heat exchanger, an indoor airfan, and indoor air outlet. The outdoor blower circuit comprises anoutdoor air inlet, an outdoor heat exchanger, an outdoor air fan, and anoutdoor air outlet. The refrigerating cycle comprises an indoor heatexchanger, an outdoor heat exchanger, a compressor, and a throttle,which are connected by piping. The air conditioner is a variablecapacity type including a compressor capable of varying capacity in twolevels by switching between FULL and SAVE. The air conditioner isprovided with a voltage detector, so that when the supply voltage isbelow a predetermined value, the compressor can be operated at SAVE. Asa result, the air conditioning operation can be continued withoutcausing a shutdown of the compressor in a low voltage environment.Furthermore, the capacitor capacity can be increased by providing aplurality of running capacitors for the compressor so as to increase thetorque of the motor in the compressor. This can reduce the probabilityof breakdown and increase the number of revolutions of the compressor soas to maintain the air conditioning performance. As a result, the airconditioning operation can be continued without causing a shutdown ofthe compressor.

The air conditioner of the present invention may be provided with acurrent detector, so that when the operating current exceeds apredetermined value, the compressor can be operated at SAVE. As aresult, when the operating current is increased in a low voltageenvironment or in an overloaded condition, the air conditioningoperation can be continued without causing a shutdown of the compressor.Furthermore, the capacitor capacity can be increased by providing aplurality of running capacitors for the compressor so as to increase thetorque of the motor in the compressor. This can reduce the probabilityof breakdown and increase the number of revolutions of the compressor soas to maintain the air conditioning performance. As a result, the airconditioning operation can be continued without causing a shutdown ofthe compressor.

The air conditioner of the present invention may be provided with adischarge pressure detector for the compressor, so that when thedischarge pressure exceeds a predetermined value, the compressor can beoperated at SAVE. Thus, in an overloaded condition, the air conditioningoperation can be continued without causing a shutdown of the compressor.Furthermore, the capacitor capacity can be increased by providing aplurality of running capacitors for the compressor so as to increase thetorque of the motor in the compressor. This can reduce the probabilityof breakdown and increase the number of revolutions of the compressor soas to maintain the air conditioning performance. As a result, the airconditioning operation can be continued without causing a shutdown ofthe compressor.

The air conditioner of the present invention may be provided with atemperature detector for the outdoor heat exchanger, so that when thetemperature of the outdoor heat exchanger exceeds a predetermined value,the compressor can be operated at SAVE. As a result, even in anoverloaded condition, the air conditioning operation can be continuedwithout causing a shutdown of the compressor. Furthermore, the capacitorcapacity can be increased by providing a plurality of running capacitorsfor the compressor so as to increase the torque of the motor in thecompressor. This can reduce the probability of breakdown and increasethe number of revolutions of the compressor so as to maintain the airconditioning performance. As a result, the air conditioning operationcan be continued without causing a shutdown of the compressor.

The following is a description of embodiments of the present inventionwith reference to drawings. Note that the present invention is notlimited to the embodiments described below. There are two methods forincreasing a capacitor in the present invention. The first one is toincrease the number of capacitors connected in parallel to each other.The second one is to decrease the number of capacitors connected inseries to each other.

First Embodiment

A first embodiment of the present invention will be described as followswith reference to FIGS. 1 and 2.

As shown in FIGS. 1 and 2, an air conditioner of the present embodimentcomprises controller 1, compressor 2 capable of varying discharge volumein two levels between full-power operation (FULL) and power-savingoperation (SAVE), and voltage detector 3 for detecting a power supplyvoltage and transmitting the detected value to controller 1. When thevoltage detected by voltage detector 3 is below a predetermined powersupply voltage set by controller 1, compressor 2 is operated at thepower-saving operation. The air conditioner thus structured can performair conditioning operation while reducing the load of the compressor andpreventing the overload protector (OLP) from being actuated when thepower supply voltage is low in unstable voltage areas.

Second Embodiment

A second embodiment of the present invention will be described asfollows with reference to FIGS. 3 and 4.

As shown in FIGS. 3 and 4, an air conditioner of the present embodimentcomprises controller 1, compressor 2 capable of varying discharge volumein two levels between full-power operation and power-saving operation,current detector 4 for detecting an operating current and transmittingthe detected value to controller 1. When the current detected by currentdetector 4 exceeds a predetermined operating current set by controller1, compressor 2 is operated at the power-saving operation.

The air conditioner thus structured can perform air conditioningoperation while reducing the load of the compressor and preventing theOLP from being actuated when the operating current is high in unstablevoltage areas.

Third Embodiment

A third embodiment of the present invention will be described as followswith reference to FIGS. 5 and 6.

As shown in FIGS. 5 and 6, an air conditioner of the present embodimentcomprises controller 1, compressor 2 capable of varying discharge volumein two levels between full-power operation and power-saving operation,and discharge pressure detector 5 for detecting a discharge pressure andtransmitting the detected value to controller 1. When the dischargepressure detected by discharge pressure detector 5 exceeds apredetermined discharge pressure set by controller 1, compressor 2 isoperated at the power-saving operation.

The air conditioner thus structured can perform air conditioningoperation while reducing the load of the compressor and preventing theOLP from being actuated when an increase in the outdoor temperatureoverloads the refrigerating cycle and hence increases the dischargepressure.

Fourth Embodiment

A fourth embodiment of the present invention will be described asfollows with reference to FIGS. 7 and 8.

As shown in FIGS. 7 and 8, an air conditioner of the present embodimentcomprises controller 1, compressor 2 capable of varying discharge volumein two levels between full-power operation and power-saving operation,and outdoor-heat-exchanger-temperature detector 6 for detecting thetemperature of the outdoor heat exchanger and transmitting the detectedvalue to controller 1. When the temperature detected byoutdoor-heat-exchanger-temperature detector 6 exceeds a predeterminedtemperature of the outdoor heat exchanger set by controller 1,compressor 2 is operated at the power-saving operation.

The air conditioner thus structured can perform air conditioningoperation while reducing the load of the compressor and preventing theOLP from being actuated when an increase in the outdoor temperatureoverloads the refrigerating cycle and hence increases the dischargepressure.

Fifth Embodiment

A fifth embodiment of the present invention will be described as followswith reference to FIG. 9.

As shown in FIG. 9, an air conditioner of the present embodimentcomprises operation switch 10, controller 11, variable-capacitycompressor 12 capable of varying capacity in two levels between FULL andSAVE, and FULL/SAVE selector 13 for detecting an operation start signaland transmitting the signal to variable-capacity compressor 12. When theoperation start signal from operation switch 10 is detected,variable-capacity compressor 12 is operated at SAVE.

The air conditioner of variable capacity type thus structured can startoperation at low current values while reducing the compression load evenin an overloaded condition or in a low power-supply voltage environment.

Sixth Embodiment

A sixth embodiment of the present invention will be described as followswith reference to FIGS. 10 and 11.

Hereinafter the sixth embodiment a compressor is driven by a capacitorstart and run single-phase induction motor(in the present embodimentvariable-capacity compressor 12 corresponds). The motor is provided withrunning-capacitor block 14 including a plurality of running capacitors.As shown in FIGS. 10 and 11, an air conditioner of the presentembodiment comprises operation switch 10, controller 11,variable-capacity compressor 12 capable of varying capacity in twolevels between FULL and SAVE, and FULL/SAVE selector 13 for detecting anoperation start signal and transmitting the signal to variable-capacitycompressor 12. When the operation start signal from operation switch 10is detected by running-capacitor block 14, the running capacitors areconnected to each other to increase the capacitor capacity, so thatvariable-capacity compressor 12 is operated at SAVE.

The air conditioner of variable capacity type thus structured canachieve high starting performance even in an overloaded condition or ina low power-supply voltage environment, thereby successfully startingoperation.

Seventh Embodiment

A seventh embodiment of the present invention will be described asfollows with reference to FIGS. 12 and 13.

As shown in FIGS. 12 and 13, an air conditioner of the presentembodiment comprises controller 20, variable-volume compressor 21capable of varying compression discharge volume in two levels betweenFULL and SAVE, voltage detector 23 for detecting a power supply voltageand transmitting the detected value to controller 20, and FULL/SAVEselector 22 for transmitting the detected value to variable-volumecompressor 21. When the voltage detected by voltage detector 23 is belowa predetermined power-supply voltage set by controller 20,variable-volume compressor 21 is operated at SAVE. When variable-volumecompressor 21 is operated at SAVE as a result of the detection of thelow power-supply voltage by voltage detector 23, controller 20 transmitsa signal to compressor-running-capacitor block 27 so as to connectcompressor-running-capacitors to each other, thereby increasing thecompressor-running-capacitor capacity.

The air conditioner thus structured can continue air conditioningoperation while reducing the load of the compressor and preventing theOLP from being actuated when the power supply voltage is low in unstablevoltage areas.

Eighth Embodiment

An eighth embodiment of the present invention will be described asfollows with reference to FIGS. 14 and 15.

As shown in FIGS. 14 and 15, an air conditioner of the presentembodiment comprises controller 20, variable-volume compressor 21capable of varying compression discharge volume in two levels betweenFULL and SAVE, current detector 24 for detecting an operating currentand transmitting the detected value to controller 20, and FULL/SAVEselector 22 for transmitting the detected value to variable-volumecompressor 21. When the current detected by current detector 24 exceedsa predetermined operating current set by controller 20, variable-volumecompressor 21 is operated at SAVE. When variable-volume compressor 21 isoperated at SAVE as a result of the detection of the low operatingcurrent by current detector 24, controller 20 transmits a signal tocompressor-running-capacitor block 27 so as to connect compressorrunning capacitors to each other, thereby increasing thecompressor-running-capacitor capacity.

The air conditioner thus structured can perform air conditioningoperation while reducing the load of the compressor and preventing theOLP from being actuated when the operating current of the compressor ishigh in unstable voltage areas.

Ninth Embodiment

A ninth embodiment of the present invention will be described as followswith reference to FIGS. 16 and 17.

FIG. 17 is a block diagram of the ninth embodiment of the presentinvention. As shown in FIG. 16 and 17, an air conditioner of the presentembodiment comprises controller 20, variable-volume compressor 21capable of varying compression discharge volume in two levels betweenFULL and SAVE, discharge pressure detector 25 for detecting a dischargepressure and transmitting the detected value to controller 20, andFULL/SAVE selector 22 for transmitting the detected value tovariable-volume compressor 21. When the discharge pressure detected bydischarge pressure detector 25 exceeds a predetermined dischargepressure set by controller 20, variable-volume compressor 21 is operatedat SAVE. When variable-volume compressor 21 is operated at SAVE as aresult of the detection of the overloaded refrigerating cycle bydischarge pressure detector 25, controller 20 transmits a signal tocompressor-running-capacitor block 27 so as to connect compressorrunning capacitors to each other, thereby increasing thecompressor-running-capacitor capacity.

The air conditioner thus structured can perform air conditioningoperation while reducing the load of the compressor and preventing theOLP from being actuated when an increase in the outdoor temperatureoverloads the refrigerating cycle and hence increases the dischargepressure.

Tenth Embodiment

A tenth embodiment of the present invention will be described as followswith reference to FIGS. 18 and 19.

As shown in FIGS. 18 and 19, an air conditioner of the presentembodiment comprises controller 20, variable-volume compressor 21capable of varying compression discharge volume in two levels betweenFULL and SAVE, outdoor-heat-exchanger-temperature detector 26 fordetecting the temperature of the outdoor heat exchanger and transmittingthe detected value to controller 20, and FULL/SAVE selector 22 fortransmitting the detected value to variable-volume compressor 21. Whenthe temperature detected by outdoor-heat-exchanger-temperature detector26 exceeds a predetermined temperature of the outdoor heat exchanger setby controller 20, variable-volume compressor 21 is operated as SAVE.When variable-volume compressor 21 is operated at SAVE as a result ofthe detection of the high temperature of the outdoor heat exchanger byoutdoor-heat-exchanger-temperature detector 26 controller 20 transmits asignal to compressor-running-capacitor block 27 so as to connectcompressor running capacitors to each other, thereby increasing thecompressor-running-capacitor capacity.

The air conditioner thus structured can perform air conditioningoperation while reducing the load of the compressor and preventing theOLP from being actuated when an increase in the outdoor temperatureoverloads the refrigerating cycle and hence increases the dischargepressure.

The compressor can be started easily without being shut down, therebyallowing the air conditioner to start operation even in an overloadedcondition or in a low power-supply voltage environment.

The air conditioner of the present invention comprises avariable-capacity compressor capable of varying capacity in two levelsby switching between FULL and SAVE. Starting the air conditioner at SAVEenables the variable-capacity compressor to be started without beingshut down in an overloaded condition or in a low power-supply voltageenvironment. Therefore, the air conditioner can be applied not only toan air conditioner of variable capacity type but also to a dehumidifieror a drier.

1. An air conditioner of variable capacity type which comprises acompressor capable of varying capacity in two levels by switchingbetween full-power operation and power-saving operation and which isprovided with a voltage detector, wherein when a supply voltage is belowa predetermined value, the compressor is operated at the power-savingoperation.
 2. The air conditioner of claim 1, wherein the compressor isdriven by a capacitor start and run single-phase induction motor, andwhen the compressor is operated at the power-saving operation, aplurality of running capacitors are connected to each other to increasea capacitor capacity.
 3. An air conditioner of variable capacity typewhich comprises a compressor capable of varying capacity in two levelsby switching between full-power operation and power-saving operation andwhich is provided with a current detector, wherein when an operatingcurrent exceeds a predetermined value, the compressor is operated at thepower-saving operation.
 4. The air conditioner of claim 3, wherein thecompressor is driven by a capacitor start and run single-phase inductionmotor, and when the compressor is operated at the power-savingoperation, a plurality of running capacitors are connected to each otherto increase a capacitor capacity.
 5. An air conditioner of variablecapacity type which comprises a compressor capable of varying capacityin two levels by switching between full-power operation and power-savingoperation and which is provided with a discharge pressure detector forthe compressor, wherein when a discharge pressure exceeds apredetermined value, the compressor is operated at the power-savingoperation.
 6. The air conditioner of claim 5, wherein the compressor isdriven by a capacitor start and run single-phase induction motor, andwhen the compressor is operated at the power-saving operation, aplurality of running capacitors are connected to each other to increasea capacitor capacity.
 7. An air conditioner of variable capacity typewhich comprises a compressor capable of varying capacity in two levelsby switching between full-power operation and power-saving operation andwhich is provided with a temperature detector for an outdoor heatexchanger, wherein when a temperature of the outdoor heat exchangerexceeds a predetermined value, the compressor is operated at thepower-saving operation.
 8. The air conditioner of claim 7, wherein thecompressor is driven by a capacitor start and run single-phase inductionmotor, and when the compressor is operated at the power-savingoperation, a plurality of running capacitors are connected to each otherto increase a capacitor capacity.
 9. An air conditioner of variablecapacity type which comprises a compressor capable of varying capacityin two levels by switching between full-power operation and power-savingoperation, wherein the compressor starts operation at the power-savingoperation.
 10. The air conditioner of claim 9, wherein the compressor isdriven by a capacitor start and run single-phase induction motor, andthe compressor starts operation at the power-saving operation, and at asame time, a plurality of running capacitors are connected to each otherto increase a capacitor capacity.